This study examined the effect of crop rotations and winter cover crops (CCs) on near‐surface pore characteristics of a silty clay loam soil in a 27‐yr no‐till field experiment. The crop rotation treatments included a 2‐yr corn (Zea mays L.)–soybean [Glycine max L. (Merr.)] (CS) rotation and a 4‐yr corn–soybean–oat (Avena sativa L.)–winter wheat (Triticum aestivum L.) (CSOW) rotation. The subplot treatment was CC and no‐CC (fallow). Intact soil cores (7.62 by 7.62 cm) were extracted from each treatment in July 2018 from soybean plots and examined for X‐ray computed tomography (CT)‐measured pore parameters and other soil physical and hydrological properties. Data showed that, compared with fallow, the CC reduced bulk density (ρ_b) by 6% and increased saturated hydraulic conductivity (K_sat) and water infiltration rate (q_s) by 1.5 times. Soils under CSOW rotation had 16, 14, and 4% higher values of soil organic carbon (SOC), total nitrogen (TN), and wet aggregate stability (WAS) compared with those under CS rotation, respectively. The CSOW rotation significantly (P < .05) increased number of CT‐measured pores, number of macropores (>1,000 μm diameter), coarse mesopores (226–1,000 μm diameter), macroporosity, and mesoporosity compared with the CS system. The CT‐measured total porosity, number of macropores, and macroporosity were 43, 34, and 60%, respectively, higher with CC as compared to the fallow plots. The CT‐measured pore parameters were well correlated with soil ρ_b, K_sat, q_s, SOC, TN, and WAS. This study emphasizes that cropping systems that include diverse crop rotations (CSOW) and CC has potential to enhance SOC, pore characteristics, and associated physical and hydrological properties.

中文翻译：

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X射线计算机断层扫描-受作物轮作和覆盖作物影响的土壤孔隙参数

这项研究在27年的免耕田间试验中研究了轮作和冬季覆盖作物（CCs）对粉质粘土壤土近表面孔隙特征的影响。轮作处理包括2年玉米（Zea mays L。）-大豆[ Glycine max L.（Merr。）]（CS）轮作和4年玉米-大豆-燕麦（Avena sativa L。）-冬季小麦（Triticum aestivum L.）（CSOW）轮作。子图处理为CC和无CC（休假）。2018年7月，每种处理均从大豆田中提取了完整的土壤核心（7.62 x 7.62厘米），并进行了X射线计算机断层扫描（CT）测得的孔隙参数以及其他土壤物理和水文特性的检验。数据显示，与休耕相比，CC降低了堆密度（ρ_b）增加了6％，饱和水导率（K _sat）和水渗透率（q _s）增加了1.5倍。与CS轮作相比，CSOW轮作下的土壤的有机碳（SOC），总氮（TN）和湿集料稳定性（WAS）分别高16、14和4％。CSOW旋转显着（P <.05）与CS系统相比，CT测量的孔数量，大孔（直径> 1,000μm），粗中孔（直径226–1,000μm），大孔和中孔数量增加。CT测得的总孔隙度，大孔隙数和大孔隙率分别比休耕图高43％，34％和60％。的CT-测量孔隙参数以及与土壤相关ρ _b，ķ_坐着，q_小号，SOC，TN，和WAS。这项研究强调指出，包括不同轮作（CSOW）和CC的种植系统具有增强SOC，孔隙特征以及相关的物理和水文特性的潜力。